Iron alloy



- Patented Sept. 24, 1929 UNITED s TES' COMPANY, INCORPORATED,

or 'ANSONIA, CONNECTICUT i IRON ALLOY v o No Drawing. Original The present invention relates to an improvement in the manufacture of cast iron, or ferrous alloys having the chemical characteristics of cast iron, that is, which have 1'- carbon' in excess of 2.25%.

The present application is a division of my copending application, Serial No. 250,958,

\ filed January 31, 1928.

The cast iron embodying my invention may be in the form of gray iron, or chilled cast iron'or acid resisting iron and is particularly useful for the' manufacture of chilled rolls for rolling mills and similar articles which are subjected to heavy strains or loads, and to sudden changes in temperature over a wide range. Such rolls must have a hard surface to resist the wear to whichthey are subjected, and have great strength, particularly when they are of considerable length and diameter. The tendency in modern rolling mill practice is towards increased production with the same amount, or even a less amount ofequipment, through increased speed on the part of the mill rolls", and greater reduction in each pass. At the same time, ef-

forts are being made to reduce power losses through friction, particularly in the bearings of the mills, and as a result of this effort there has been created a demand for rolls so having smaller necks than those heretofore used. For these reasons, together with the fact that the rolls of a mill are being continually subjected to increased stresses, strains, shocks and vibrations as the output of the 2;; mills is stepped up, and the fact that mill rolls must stand up under peculiarly rough usage, the metal of which the rolls are composed must have extraordinary strength, toughness and durability, without sacrific- 40 those characteristics of the rollsurface which are required for the most satisfactory results on the product of the mill, and further without prejudicially affecting the cost of the roll or the facility with which it can be manufactured. Such rolls can be made of steel but cast iron is much more desirable as the cost of finished rolls may be anywhere from a half to a fifth of the cost of steel rolls of the same dimensions. However, it has been found in the past that cast iron rolls of application filed January 31, 1928, Serial No. 250,958. Divided and this application filed August 1, 1929. Serial No. 382,837.

large dimensions frequently break in service, or crack or split. This has-been thought .to be due to the loads to which they are subjected and attempts have been made to overcome this by increasing the thickness in the case of hollow rolls 'or by strengthening the lizatiarial in the case of solid rolls, or by using s cc I have discovered, however, that by using a combination of proper amounts of certain alloying elements in certain definite proportions, a cast iron alloy is produced having entirely novel characteristics and at a cost only slightly in excess of ordinary cast iron and that. chilled rolls and other similar articles subjected to heat and stresses and'made from my novel cast iron are much stronger and more durable and are not subject to the defects' heretofore commonly observed in such rolls.

' The invention is based in part on the discovery that the breakage of chilled rolls is not ordinarily due to the stresses to which they are subjected by their loads but is due to the different rate of expansion. 7 of the chilled and gray iron (unchilled), portions; and in part to the discovery that the presence of certain alloying elements tends to vary the co-efficients of expansion of the chilled iron and the gray iron portions respectively and also the distribution of heat throughout the mass can be thereby varied so that it will not set up so great stresses in the article.

In practice, I find that small amounts of copper in the presence of small but suflicient quantities of molybdenum gives .to the cast iron the characteristics required and that the hardness required can be attained by the use of chromium in quantities determined by the use to which the roll is to be put, without destroying the effects of the copper and molybdenum. The depth of chill required can be regulated by the amount of silicon or other suitable elements, which counteract the tendency of the copper to reduce the depth of chill and by the proper balancing of the several elements, as will be apparent to those skilled in the art. Manganese, sulphur and phosphorus will also be presentin quantities PATENT oFFlc I additions, including silicon is melted in a according to the uses to which the finished material is to be put, it being understood that manganese is normally'a hardening element, but that in the presence of sulphur depending on the ratio ofthe two it tends to soften the product. i

In forming the. alloy and casting the same, the more or less usual process used in the production of iron for casting is not unduly .complicated. The charge made up as'usual of pig iron and scrap, together with the alloy suitable furnace, or added ln'the ladle.

For chilled rolls the proportions may be within the following ranges: carbon, more than 2.25%; copper, from 0.25 to 1.00%; molybdenum, from 0.10 to 0.75%; silicon, more than 0.25%; sulphur, from 0.02 to 0.18%, the balance to make up 100% being iron except for usual impurities.

The herein described-compositions while havingthe desired physical characteristics can be made at relatively low costsince copper is a very cheap alloying element and the amount of molybdenum required is'small, the result being that the final cost even when chromium is used is exceedingly low considering the'qualities of the articles produced.

I believe myself to be the first to recognize the fact that by the use of certain alloying elements and particularly those mentioned herein .it is possible to control and regulate the thermal effects and properties of articles, especially chilled rolls which are subjected to heavy loads and changes of temperature over wide ranges, and thereby to overcome the defects which have been erroneously thought in the past to have been due to insuflicient strength.

What I claim is: 1. A cast iron alloy containing as essential elements carbon more than 2.25%, copper from 0.25%to 2% and molybdenum 0.10%

- hand this 31st 2. A cast iron alloy containing as essential elements carbon more than 2.25%, cop- 'per from 0.25% to 1% and molybdenum from 0.10to .75%.

3. A castiron alloy chilled roll containing as essential elements carbon 3%, copper 0.50%; and "molybdenum 0.50%. Q

4. cast iron allo containing as essential elements'copper in e ective amount and more than 2.25% carbon, together with from 0.10% l to 2% molybdenum.

In witness whereof, I have hereunto set my day of July, 1929. ALAN F. HILTON. 

